Carpet and carpet making methods

ABSTRACT

The disclosure relates to a carpet product, a process for manufacturing carpet, and an apparatus used in a carpet manufacturing process. The carpet product is made from tufted polymer filament yarn wherein the individual yarn filaments of the yarn back loops are integrally fused so that the carpet resists fuzzing. The primary backing preferably is modified polypropylene in the fill direction. Further, the primary backing may be coated with a polymer before tufting to adhere or integrally fuse the inside of the fiber tuft to the primary backing. An optional secondary backing is preferably made of tape yarn in both directions. The process includes providing a carpet base having a primary backing penetrated by yarn, applying heat to the underside of the primary backing, extruding a heated sheet of polymer and continuously contacting the heated extruded sheet of polymer with the base. The apparatus includes a source of carpet precursor, a heated cylinder for heating the underside of the carpet, an extruder and a casting roll against which the extruded sheet and heated carpet are pressed.

RELATED APPLICATIONS AND PATENTS

[0001] This application is a continuation of application Serial No.09/289,581 filed Apr. 12, 1999, the contents of which is herebyincorporated by reference.

FIELD OF THE DISCLOSURE

[0002] The application relates to pile carpet and, in particular, to acarpet in which the face yarn is secured to one or more backing layers.Apparatus and methods for manufacturing such carpet are also disclosed.

BACKGROUND

[0003] Most carpets are composite structures in which the face fiberforming the pile, i.e., the surface of the carpet, penetrates at leastone backing layer. The base portions of the facing yarn extend throughthe backing and are exposed on the bottom surface of the primarybacking. Such carpets, generally termed tufted carpets, may be cut pileor loop pile. Aspects of the present invention are also applicable tomost other types of carpet, including woven or knitted carpets such asBerber carpets and certain sports surfaces, such as artificial turf orgrass.

[0004] The basic manufacturing approach to the commercial production oftufted carpeting is to start with a woven scrim or primary carpetbacking and to feed this into a tufting machine or a loom. The carpetface fiber is needled through and embedded in the primary carpetbacking, thus forming a carpet precursor or base, sometimes calledgreige goods. Upstanding loops on the upper side of the carpet may becut to produce cut pile carpet. Yarn loops or knots are usually exposedon the underside of the greige goods.

[0005] Greige goods are typically backed with an adhesive coating inorder to secure the face yarn to the primary backing. Low cost carpetoften receives only a latex adhesive coating as the backing. This typeof carpet is widely used in boats and is called marine backed carpet.Typically, the marine backed carpets are backed with a latex adhesivecoating that is water and/or mildew resistant. Higher cost carpet oftenreceives both a latex adhesive coating and a secondary backing.

[0006] The face fiber or yarn used in forming the pile of a tuftedcarpet is typically made of any one of a number of types of fiber, e.g.,nylon, acrylic, polypropylene, polyethylene, polyester, rayon, wool,cotton and the like. Face yarns used in carpet include spun staple yarnand bulk continuous filament (BCF) yarn which is made up of tens orhundreds of individual fibers, generally about 50-200 individual fibers,though more or less fibers can be used. Fibrillated polypropylene grassyarn is also often used as a face yarn.

[0007] The individual yarn, once made, is often twisted by itself or incombination with two or more yarns to increase the total denier. Forexample, two yarns of 1500 denier each can be twisted together toproduce a 3000 denier yarn, or three yarns of 1000 denier each can betwisted together to produce a 3000 denier yarn made up of BCF or spunstaple feeder yarn. The two or more yarns can be the same color ordifferent colors. Thus, a much wider range of yarn deniers andcolorations is made possible. The yarns often are textured or airentangled to achieve a different appearance. The twisting, texturing andair entangling may require that the yarn receive a spin finish thatmakes the yarn surface easier to work with in the fiber processing.However, the spin finish complicates adhesion of other materials inlater processing, for example, in coating the yarns.

[0008] Primary backings for tufted pile carpets are typically woven ornon-woven fabrics made of one or more natural or synthetic fibers oryarns, such as jute, wool, polypropylene, polyethylene, polyester,nylon, rayon and the like. Films of synthetic materials, such aspolypropylene, polyethylene and ethylene-propylene copolymers, may alsobe used to form the tape for weaving the primary backing. When tapeyarns are used, they are woven into a backing fabric which may consistof the same or different materials in the warp and fill directions. Thecarpet face fiber is usually embedded in the primary backing such thatit wraps around the fill material.

[0009] The application of the latex adhesive to the primary backinginvolves coating the bottom surface of the formed greige goods with alatex polymer binder such as a styrene-butadiene copolymer. Theviscosity of the latex adhesive is similar to water and the latexadhesive flows relatively easily into the back of the carpet, wettingout the fiber bundles and penetrating the primary backing. The coatedgreige goods are passed through an oven to dry the latex adhesivecoating. In this manner, the face fibers are attached to the primarybacking by the latex binder.

[0010] It is known in the art to prepare the greige goods for coating bysubjecting the back of the greige goods to a gas flame to reduce thebulk of the protruding face yarn, particularly in greige goods withlarge knots, in order to reduce the amount of latex adhesive necessaryto provide a smooth, well-covered surface. It is also known to applypressure and low level heat (i.e. below yarn melting temperature) toflatten the knots prior to the application of the latex adhesive.

[0011] If desired, a secondary backing may be bonded to the undersurfaceof the primary backing. To produce tufted carpets with a secondarybacking, the bottom surface of the greige goods is coated with a latexpolymer binder. The secondary backing is applied to the coated bottomsurface and the resulting structure is passed through an oven to dry thelatex adhesive coating to bond the secondary backing to the greigegoods.

[0012] Secondary backings for tufted pile carpets are typically woven ornon-woven fabrics made of one or more natural or synthetic fibers oryarns. In particular, secondary backings for tufted pile carpets areopen weave or leno weave, having tape yarn in the warp direction,usually of polypropylene, and spun staple fiber in the fill direction.The spun staple fiber is very costly, but is used to increase adhesionbetween the backing and latex adhesive coating normally used. The spunstable fiber is hairy when formed and, after the yarn is woven, it isactually run against an abrasive roll to make the spun yarn more hairy.The latex is then able to wet out all the little hairs, improvingadhesion of the secondary backing to the carpet. However, spun stapleyarn is not as strong as tape yarn. Therefore, a strong and lessexpensive secondary backing material is desirable.

[0013] The above-described methods have disadvantages in that theyrequire a drying step and thus an oven to dry the latex polymer binder.The drying step increases the cost of the carpet and limits productionspeed. Furthermore, it has been reported that latex adhesivecompositions generate gasses that may be the cause of headaches, wateryeyes, breathing difficulties and nausea, especially when used in tightlysealed buildings. See Herligy, The Carpet & Rug Industry, October 1990.An additional problem sometimes encountered with the latex coating isthat the latex may go all the way through the primary backing and ruinthe appearance of the carpet due to excessive penetration caused by thelow viscosity of the latex. In addition, overheating of the carpet mayoccur during drying of the latex, which in turn may affect the shade ofthe carpet.

[0014] Consequently, carpet manufacturers have been attempting todevelop a new approach for the preparation of tufted carpets. One suchmethod is the preparation of tufted carpets with a hot-melt adhesivecomposition instead of a latex composition.

[0015] Hot-melt adhesives are amorphous polymers that soften and flowsufficiently to wet and penetrate the backing surfaces and tuft stitchesof carpets upon application of sufficient heat. Furthermore, hot-meltadhesives tend to adhere to the backing surfaces and/or tuft stitches.

[0016] The hot-melt compositions are selected for their adhesiveproperties in adhering to the tufts of face yarn, to the primary backingand to the secondary backing, as well as adhering the various layers ofthe carpet product to each other. Such compositions are generallyamorphous or substantially non-crystalline due to the adhesiveproperties of such polymers.

[0017] By the use of hot-melt adhesive, the necessity of drying thecomposition after application is eliminated and, further, when asecondary backing material is desired, it can be applied directly after,or in conjunction with, the hot-melt composition application withoutrequiring an intervening drying step.

[0018] Application of a hot-melt composition is generally accomplishedby passing the bottom surface of the greige goods over an applicatorroll positioned in a reservoir containing the hot-melt composition in amolten state. A doctor blade is ordinarily employed to control theamount of adhesive which is transferred from the application roll to thebottom surface of the structure. Alternatively, the hot melt adhesive isextruded from a die and falls onto the greige goods, thereby coating thegreige goods. After application of the hot-melt composition to thebottom surface of the greige goods, and prior to cooling, the secondarybacking, if desired, is brought into contact with the bottom surface,and the resulting structure is then passed through nip rolls and heated.

[0019] The activation temperature of a hot-melt adhesive, i.e., thetemperature at which the adhesive softens and flows sufficiently to wetand penetrate the backing surfaces and tuft stitches, is below thetemperature at which the backing and face yarns melt or otherwisedistort. Otherwise, the backing and face yarns may suffer other damagedue to heating.

[0020] The compositions which work best as adhesives are those that canadhere to nylon or other materials from which the fibers are made. Forexample, as discussed in GB 971,958, the adhesive composition mayinclude modified olefins such as olefin copolymers of ethylene, butyleneor propylene with polar monomers such as, but not limited to, methylmethacrylate, vinyl acetate, ethyl acrylate and methyl acrylate. Theresulting carpet looks good and has many potential benefits over thelatex-coated carpet.

[0021] However, it has been found that the tensile strength of hot-meltadhesives is very low, on the order of one-tenth the tensile strength ofpolypropylene, and about one-seventh the strength of ethylenecopolymers. Therefore, hot-melt adhesive carpets generally are deficientin tuft pull strength (force required to remove a tuft from the carpet),particularly as measured by the fiberblock test or “Velcro Test,”wherein a two pound Velcro® roller approximately three and one-halfinches wide and one and one-half inches in diameter of well-known hookand loop fastening material is rolled repeatedly over the loop pile ofthe carpet, for example, ten times. The carpet is then inspected forprotruding fibers or fuzz (short individual filaments removed from thefiber bundles).

[0022] A further problem with hot-melt adhesive is that it begins toloose temperature and increase in viscosity as soon as it leaves the dieor is extracted from the reservoir. The hot-melt adhesive loses someheat to the surrounding air in the short distance from die or reservoirto carpet. The carpet further acts as a heat sink for the heat of thehot-melt adhesive, causing the viscosity to drop off sharply. Nippressure can be applied to help the hot-melt adhesive to penetrate thegreige goods, but this forces the melt against and into the relativelycold carpet, even further lowering the melt temperature and viscosity.

[0023] This is even further complicated by the fact that the carpet canbe made from yarns that have been twisted together, for example, two ormore feeder yarns twisted into one larger yarn. The tufting process mayalso stitch several yarns over each other, in effect burying yarns underoverlapping stitches, thus preventing the adhesive from reaching all ofthe fibers. Any finish or coating such as a spin finish that may havebeen originally applied to the yarn also complicates this by makingadhesion of the melt difficult. The result is that total penetration andwetting of the yarn back loops is usually not achieved and, thus, thetuft pull strength is very low.

[0024] Thus, conventional carpet and carpet manufacturing processes haveinherent problems. Specifically, the adhesives used to adhere the tuftsof face fiber to the primary backing and to adhere the secondary backingto the primary backing include compositions which require lengthy dryingtimes, thus slowing down the manufacturing process. Further, theseadhesives may excessively penetrate the fibers, distorting theappearance of the carpet face. In addition, use of latex compositions asadhesives may produce noxious gases which create health hazards. Many ofthe hot-melt adhesive compositions conventionally employed in themanufacture of carpet do not result in reproducible consistencyregarding scrim bonds (force required to remove the secondary backingfrom the finished carpet), tuft pull strength and fuzz resistance (anindication of the amount the individual carpet yarns may fuzz and formpills).

[0025] In the original parent application Ser. No. 07/883,093, now U.S.Pat. No. 5,240,530, there are disclosed certain methods for producingcarpet. According to the teachings of that application, a thermoplasticpolymer sheet may be extruded into contact with greige goods tointegrally fuse the primary backing, face yarn and extruded sheet. Cutpile carpet is presented as exemplifying the use of the methods. Nolatex or adhesive application is required, nor is a backing steprequired, though one may be employed in some products.

[0026] It is known that latex adhesives, if properly applied, canprovide sufficient binding of carpet fibers to permit manufacture ofloop pile carpets which can pass the Velcro® test. It is important thatany proposal to replace the use of conventional adhesives be likewisecapable of producing a carpet in which the face yarn or fibers aresecurely attached to the carpet, and, in particular, capable ofproducing loop pile carpet made with bulk continuous filament (BCF) faceyarn or spun staple yarn which can pass the Velcro® test.

[0027] The present application includes disclosure of improved carpetsand improved techniques for manufacturing carpets which retain variousadvantages of the carpets and methods initially disclosed in theoriginal parent application.

SUMMARY OF THE DISCLOSURE AND OBJECTS OF THE INVENTION

[0028] The present disclosure relates to a novel carpet product andmethod and apparatus for producing such a carpet. The present disclosurefurther relates to an improved carpet and method for producing a carpetthat overcomes many of the problems associated with a conventionalcarpet and carpet manufacturing processes.

[0029] The present disclosure particularly relates to a carpet having atleast a primary backing, a yarn made up of a plurality of thermoplasticfibers wherein the yarn is tufted in the primary backing with back loopsof fiber on the underside of the primary backing wherein a portion ofsubstantially all of the plurality of fibers is integrally fusedtogether, and a greige goods coating of a thermoplastic polyolefinpolymer having recurring polar moieties which contacts one or more ofthe integrally fused fibers and primary backing.

[0030] The present disclosure further relates to a process formanufacturing a carpet including tufting a primary backing with a yarnto form a carpet base having portions of the yarn protruding from theupper side of the primary backing and back loop portions of the yarnexposed on the underside of the primary backing, heating the undersideof the carpet base to heat the back loop portions of the yarn tointegrally fuse individual fibers of the yarn together, and applying agreige goods coating of thermoplastic polyolefin polymer havingrecurring polar moieties directly to the underside of the carpet base toadhere or integrally fuse a portion of substantially all the fibers inthe back loops.

[0031] A further object of the invention is a carpet having a primarybacking coated on one side with a primary backing coating ofthermoplastic polyolefin polymer having recurring polar moieties whereina face yarn made of a plurality of fibers in a fiber bundle is tuftedthrough the coated primary backing, having back loops on the undersideof the coated primary backing, which adhere or integrally fuse thereto,and a greige goods coating comprising a second thermoplastic polyolefinpolymer having recurring polar moieties contacting one or more of thefiber back loops and coated primary backing.

[0032] Another object of the invention is a method for manufacturing acarpet including coating a primary backing with a primary backingcoating of thermoplastic polyolefin polymer having recurring polarmoieties, fixing tufts of carpet fibers to the coated primary backing sothat the tufts protrude from the top surface of the coated primarybacking to form a tufted base and back loop portions of the carpetfibers are exposed on the underside of the primary backing, contactingthe lower surface of the tufted base with a greige goods coating ofthermoplastic polyolefin polymer having recurring polar moieties, andadhering or integrally fusing at least one of the coated primary backingor fiber back loops to the greige goods coating.

[0033] It is a further object of the invention that the primary backingadhere or integrally fuse to the yarn fibers. Preferably, the primarybacking comprises at least in either the warp or fill direction athermoplastic polyolefin polymer having recurring polar moieties,allowing the fibers of the face yarn to better adhere to the primarybacking around which they are wrapped, thereby preventing pull-out ofthe fibers. Advantageously, the thermoplastic polyolefin polymer havingrecurring polar moieties is in the fill direction. Further, it ispreferable that the thermoplastic polyolefin polymer having recurringpolar moieties for use in the primary backing is a propylene copolymeror polypropylene graft polymer. Various specific compositions areemployed in preferred embodiment of the present invention.

[0034] The present disclosure further provides a secondary backing whichcomprises polypropylene tape yarn in both the warp and fill directions,thus reducing cost and improving strength.

[0035] It is another object of the present invention to provide aprocess for manufacturing a carpet made from thermoplastic polymerswhich satisfies commercial requirements relating to resistance tofuzzing, yarn integrity, tuft binding and lamination strength.

[0036] It is another object of this invention to reduce the cost ofmanufacturing carpets.

[0037] It is a further object of this invention to improve the adhesionbetween layers binding the carpet, thereby improving carpet strength,yarn integrity, tuft binding, laminative strength and resistance tofuzzing.

[0038] The present disclosure also relates to carpet making machinery.In one embodiment, a carpet precursor is supplied to an arrangement ofrollers including a fluid heated roller which is pressed against theunderside of the carpet precursor. In a preferred embodiment, anextruder directly extrudes a hot thermoplastic sheet onto the heatedunderside of the carpet precursor. The laminate so formed is pressedagainst a cooled casting roll.

[0039] In an alternate embodiment of the present invention, a preformedsheet of thermoplastic polymer is simultaneously heated and laminatedwith a carpet precursor in an apparatus including a continuous movingsurface or belt. The belt is differentially heated so that it isrelatively hot at the location where it first contacts the polymersheet. The belt is moved and cooled so that it readily separates fromthe underside of the carpet after the carpet precursor and polymer sheethave been adhered or integrally fused.

[0040] Accordingly, it is an object of the present invention to providemachinery for producing a carpet from a carpet precursor contacting apolymer sheet.

[0041] These and other objects and features will be apparent from thedetailed descriptive material which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The figures listed below represent preferred embodiments of theinvention described herein.

[0043]FIG. 1 is a cross-sectional view of a carpet being manufactured inaccordance with a preferred embodiment of the present invention;

[0044]FIG. 2a is a cross-sectional view of a cut pile carpet precursor;

[0045]FIG. 2b is a cross-sectional view of a cut pile carpet made inaccordance with the teachings of the present invention;

[0046]FIG. 3a is a cross-sectional view of a carpet precursor for a looppile carpet;

[0047]FIG. 3b is a cross-sectional view of a loop pile carpet made inaccordance with the teachings of the present invention;

[0048]FIG. 3c is a cross-sectional view of a loop pile carpet withsecondary backing made in accordance with the teachings of the presentinvention;

[0049]FIG. 4a is a side schematic view of an apparatus used in themaking of carpet, employing a heated roller;

[0050]FIG. 4b is a pictorial view of an apparatus of the type describedgenerally in connection with FIG. 2a;

[0051]FIGS. 5a and 5 b are graphs illustrating the estimatedtemperatures of carpet components as a function of time for theapparatus of FIG. 2;

[0052]FIG. 6 is a side schematic view of an apparatus used in the makingof carpet, employing a heated plate;

[0053]FIG. 7 is a side schematic view of an apparatus used in makingcarpet employing a continuous, temperature-controlled surface; and

[0054]FIG. 8 is a cross-sectional view of a loop pile carpet with acoated primary backing made in accordance with the teachings of oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] According to the present invention, a thermoplastic polymer sheetis laminated with a carpet precursor to form a carpet product withdesirable physical properties. Generally, the carpet precursor is madeof a face yarn which interpenetrates a primary backing or grid definingthe plane of the finished carpet. The carpet precursor may be woven orknitted.

[0056] In preferred embodiments, the carpet precursor has face yarntufted in a primary backing and integrally fused to itself. A greigegoods coating of thermoplastic polyolefin polymer having recurring polarmoieties is contacted with the underside of the formed carpet precursor.A carpet product with excellent physical properties may be made usingthe techniques and apparatus described as follows.

[0057] The carpet of the present disclosure is desirably prepared byfeeding a primary carpet backing into a conventional tufting machine.During the tufting process, carpet face yarn is also fed into thetufting machine wherein hundreds of individual tufting needles may beemployed to stitch through the primary carpet backing, thus forming acontinuous web of face fiber tufted through the primary backing. At thispoint, the carpet face fiber is secured to the backing to a degreesufficient for movement of the tufted material for further processing,but not sufficient for its use as a finished carpet. The tufted fibersremoved from the tufting machine are called greige goods.

[0058] The greige goods taken from the tufting machine are finished tomake the material suitable for finished carpet. First, the greige goodsare preferably heated to melt the tufted fibers together within theprimary backing, thereby integrally fusing the tufted fibers tothemselves and/or to the primary backing. After fusing the tuftedfibers, a greige goods coating comprising a thermoplastic polyolefinpolymer having recurring polar moieties is applied to the underside ofthe greige goods at a temperature sufficiently high so as to create aheat bond between the primary backing layer and/or carpet face fiber andthe greige goods coating. A temperature sufficiently high to create aheat bond is a temperature at least equal to the melting temperature ofthe greige goods coating. More preferably, a temperature sufficientlyhigh enough to create a bond is a temperature at least about 100° F.higher than the melting point of the greige goods coating, even morepreferably at least about 125° F. higher, and even more preferably atleast about 150° F. higher than the melting point of the greige goodscoating. For example, if the greige goods coating is polypropylene, apreferred temperature is at least about 450° F., more preferably atleast about 475° F., even more preferably at least about 500° F. Ofcourse, temperatures too high may result in unwanted degradation of thepolymers.

[0059]FIG. 1 illustrates some of the features of a carpet product of apreferred embodiment of the present invention. A primary backing layeris designated by the numeral 10. Face yarn is tufted in the primarybacking forming a yarn pile 12 on the upper side of the carpet and backloops or knots 14 on the bottom. The tufted primary backing 16 isreferred to here as the carpet precursor, carpet base or greige goods.On the left-hand side of FIG. 1, the carpet face yarn is loosely securedto the backing 10 by the tufting process to a degree sufficient formovement of the precursor for further processing, but the precursor isnot sufficiently mechanically stable for use as a finished carpet.

[0060] The carpet precursor is desirably heated to a temperaturesufficient to cause melting of the back loops such that at least aportion of substantially all of the fibers therein integrally fusetogether and/or at least a portion of the back loops integrally fusewith other back loops.

[0061] The precursor is then laminated with a greige goods coating 18 ina thickness of from about 3 to 15 mils to form the carpet product 20.Advantageously, the greige goods coating is a thermoplastic polyolefinpolymer having recurring polar moieties. The carpet precursor is adheredto or integrally fused with the greige goods coating.

Carpet Products

[0062]FIG. 1 illustrates a preferred embodiment of the presentinvention: a carpet product including a face yarn and a backing materialcoated with a polymer.

[0063] More specifically, preferred embodiments of the carpet maycomprise a primary backing, a face yarn protruding from a top surface ofthe primary backing, where the fibers of the face yarn are integrallyfused, and a greige goods coating of a thermoplastic polyolefin polymerhaving recurring polar moieties adhered or integrally fused to the backloops of the face yarn and/or to the bottom surface of the primarybacking.

[0064] The primary backing may preferably be a polypropylene woven ornon-woven material wherein the fill yarn is a thermoplastic polyolefinpolymer having recurring polar moieties to better facilitate adherenceto or integral fusing with the inside of the fiber bundle back loop.

[0065] Alternatively, the primary backing may be coated with athermoplastic polyolefin polymer having recurring polar moieties beforetufting. Again, this facilitates better adherence to or integral bondingbetween the primary backing and the inside of the fiber bundle backloop. Further, because this primary backing coating may adhere orintegrally fuse with the greige goods coating, it further helps to lockthe fiber bundle in place on the primary backing, preventing pull-outand fuzzing of the fibers.

[0066] The carpet product of the present invention may also include oneor more secondary backing layers adhered or integrally fused to thecarpet precursor by a greige goods coating. Preferably, the secondarybacking comprises tape yarn in both the warp and fill direction.

[0067] The tufts of fiber protruding from the top surface of the primarybacking layer may be of any of the conventionally used fibers or yarnsfor tufting carpet. Such materials preferably include nylon, polyesterand polypropylene, or other thermoplastic synthetic materials when thefibers are to be integrally fused to themselves. However, the yarns caninclude any of the natural or synthetic fibers known by those skilled inthe art. The fibers protruding from the primary backing may be made ofthe same material as the primary backing itself.

[0068] Any one or more of the face yarn, primary backing, primarybacking coating, secondary backing and greige goods coating may comprisethe same thermoplastic polymer. Preferably, the thermoplastic polymer isa thermoplastic polyolefin polymer having recurring polar moieties, alsotermed a “polar modified polyolefin”. As used herein, the phrase“thermoplastic polyolefin polymer having recurring polar moieties”, or“polar modified polyolefin,” is meant to include a random, impact orblock copolymer, or a graft polymer. The polyolefin copolymer comprises,for example, ethylene, propylene or butylene and polar monomersincluding, but not limited to, methacrylate, vinyl acetate, acrylicacid, methacrylic acid, ethyl acrylate, butyl acrylate and vinylalcohol. The graft polymers comprise, for example, polyethylene,polypropylene or polybutylene having a polar moiety grafted thereon,wherein the polar moiety is preferably maleic anhydride (MAH). Modifiedpolypropylene as used herein is meant to include both the copolymers ofpropylene and graft polymers of polypropylene set forth above. A polymerof polyolefin and an acrylate as used herein is meant to include acopolymer of ethylene, propylene or butylene with one or more ofmethacrylate, ethyl acrylate or butyl acrylate, or a graft polymer ofpolyethylene, polypropylene or polybutylene with one or more ofmethacrylate, ethyl acrylate or butyl acrylate. Polymers of this typeare set forth in Table A of U.S. Pat. No. 5,240,530, herein incorporatedby reference.

[0069] In a preferred embodiment, all of the layers of the carpetcomprise the same thermoplastic polyolefin polymer having recurringpolar moieties. In this embodiment, all layers of the carpet integrallyfuse with all other layers, forming a strong carpet product.

[0070] In another embodiment, the primary and secondary backing andgreige goods coating are formed of one polymer and the face yarn isformed of a different polymer. For example, the primary and secondarybacking and greige goods coating are formed of a thermoplasticpolyolefin polymer having recurring polar moieties and the face yarn isformed of nylon or polyester, or of natural materials such as cotton orwool. In other embodiments, some or all of the backing may be formedfrom thermoplastic polyolefin polymer having recurring polar moieties.It is preferred, however, to use a polymer for the primary and secondarybackings with melting points similar to that of the greige goods coatingto facilitate adhesion to, or, preferably, integral fusion with thegreige goods coating.

[0071] In some carpets, the bottom layer (either the greige goodscoating or secondary backing) may be formed from a blend ofthermoplastic polyolefin polymer having recurring polar moieties andthermoplastic elastomer to provide some properties of the elastomer suchas flexibility, non-skid character and other properties similar torubber.

[0072] The primary backing of the carpet product may include anysynthetic resin that will integrally fuse with the greige goods coatingand may be, for example, a woven or non-woven fabric, a film or a web.Preferably, the primary backing is made of a thermoplastic polyolefinpolymer, copolymer or terpolymer in the warp direction, with athermoplastic polyolefin polymer having recurring polar moieties in thefill direction, preferably a maleic anhydride graft polymer ofpolypropylene. This facilitates adhesion or integral fusion of theinterior of the fiber bundle with the primary backing, helping toprevent pull-out of the fibers and making total penetration of theadhesive coating into the fiber bundle unnecessary.

[0073] Further, the primary backing may be coated with a thermoplasticpolymer, such as a thermoplastic polyolefin polymer having recurringpolar moieties as discussed herein throughout, before tufting of thefibers through the primary backing. The primary backing coating ispreferably in an amount of from about 0.5 to 5.0 mils thick. Coating theprimary backing before tufting promotes adhesion or integral fusion ofthe interior of the fiber bundles with the primary backing upon heating.Again, this helps to secure the fibers in place without necessitatingtotal penetration of the fiber bundle by the adhesive coating. Further,where the primary backing coating is exposed to the greige goods coatingthrough the fiber back loops, adhesion or integral fusion of the primarybacking coating and greige goods coating will occur, effectivelytrapping the fiber bundle between the primary backing coating and greigegoods coating. This increases tuft bind strength of the resultantcarpet.

[0074] The secondary backing material, if applied, may preferablyinclude any synthetic resin that will adhere or integrally fuse with thegreige goods coating. Advantageously, the secondary backing willcomprise the same thermoplastic polyolefin polymer having recurringpolar moieties as the primary backing. The secondary backing for thecarpets of the present disclosure may comprise a woven or non-wovenfabric. A woven secondary backing may be an open weave or leno weave,preferably having tape yarn in both the warp direction and in the filldirection. However, the open weave is not necessary to obtain a suitablebond as may be required with use of a latex adhesive.

[0075] The greige goods coating may be formed from a thermoplasticpolyolefin polymer having recurring polar moieties. A preferred greigegoods coating is a copolymer of ethylene or a graft polymer ofpolypropylene. Preferably, the greige goods coating is applied in anamount of from about 3 to 15 mils.

[0076] The thermoplastic polyolefin polymer having recurring polarmoieties used in the greige goods coating may be compounded with inertfillers by either extrusion compounding or mixing operations. Suchfillers may include calcium carbonate, silicates, talc, calcium, glassfibers, carbon black and wood flour. Other fillers may also be suitable.

[0077] The use of such fillers in the greige goods coating may rangefrom about 0.1 to as high as about 50%. At the high levels, anexceedingly stiff board like material may be made that may be used,e.g., as a trunk liner, molded floor mat or a door panel in anautomobile. Because addition of a filler significantly alters theperformance and process ability of the polymer, filled systems may bedesigned to satisfy a particular product need with minimum effect onother performance aspects.

[0078] It is desirable that, for some use applications, carpet made inaccordance with the present invention pass the “pill test” (ASTM D-2859)for fire resistance. Thus, in some applications where enhanced flameresistance is required, a fire-retardant may be added to the feedstockused to produce the greige goods coating.

[0079] Optionally, blends of the thermoplastic polyolefin polymershaving recurring polar moieties and thermoplastic elastomers may be usedto make the greige goods coating or co-extruded layer. The thermoplasticelastomers (TPE's) are a diverse family of rubber-like materials that,unlike vulcanized rubbers, may be processed and recycled asthermoplastics. A listing of some suitable TPE's is given in parentpatent U.S. Pat. No. 5,240,530 at Table A, column 11, which is herebyincorporated by reference. The TPE's are not merely substitutes forthermosetting polymers, but may also replace or improve theirproperties. There are four general groups of TPE's that may be suitablefor use in the present invention. The four general groups includepolyurethanes, copolyesters, styrene block copolymers, and polyolefins.Blending the elastomer with the polyolefin polymer provides some of theproperties of the elastomer at a lower cost. The compatibility is goodfor blends ranging from about 10 to 97% elastomer based on the totalamount of thermoplastic polyolefin polymer having recurring polarmoieties and elastomer.

[0080] As a class, the TPE's may provide toughness, flexibility over awide temperature range, and resistance to abrasion, weathering, and avariety of solvents and other chemicals. Thus, the properties of each ofthe materials in the group may be tailored for use in the carpet of thepresent invention by polymerization methods, blending, and incorporationof additives, fillers, and reinforcements to form carpets havingenhanced abrasion, weathering and chemical resistance.

[0081] Depending on the material composition of each of the possiblecarpet layers (yarn, primary backing, primary backing coating, greigegoods coating, secondary backing), various adjacent or overlappingcarpet layers will adhere or integrally fuse. Integral fusion istypically achieved using chemically similar thermoplastics which melttogether, while adhesion requires that the materials stick together byeither chemical or mechanical means. Adhered materials typically may beseparated into the component parts. Adhesion and integral fusion of thevarious carpet components as disclosed may provide a carpet havingimproved strength, fuzz resistance and longevity.

IMPROVED METHODS AND APPARATUS FOR CARPET MANUFACTURE

[0082] With reference to FIG. 1, an improved method of making a carpetproduct according to the invention is generally illustrated. Heat andpressure are applied (for example, by a heated roller) to the undersideof the carpet precursor at location 22 sufficient to heat the undersideof the carpet precursor to above the melting point of the face yarn.This preheating of the carpet precursor causes a portion ofsubstantially all of the fibers in the back loops of the face yarn tointegrally fuse together. Generally, the temperature should be about 50°F. above the melting point of the face yarn, preferably at least 100° F.above the melting point of the face yarn. A heated greige goods coatingof thermoplastic polyolefin polymer having recurring polar moieties 18is brought into contact with the heated carpet precursor at location 24whereby the laminated carpet product 20 is produced. The carpet productmay either be the finished carpet or subjected to further processing,e.g. application of additional backings.

[0083]FIGS. 2 and 3 illustrate, by way of example, two types of carpetproducts made in accordance with the teachings of the present invention.FIG. 2 relates to a cut pile, or grass, carpet and FIG. 3 relates to aloop pile carpet with optional secondary backing.

[0084]FIG. 2a depicts a carpet precursor 200 from which a carpet, forexample, grass carpet, is made. A woven primary backing 202 isinterpenetrated by fibrillated isotactic polypropylene yarn 204 in apreferred embodiment. Cut yarn ends or tufts 206 form the pile of thecarpet. The yarn is loosely secured in place by back loops 208 exposedon the underside of the carpet precursor. In this example the backing202 is a woven fabric made of polypropylene.

[0085]FIG. 2b depicts a carpet product 210 made from the carpetprecursor of FIG. 2a. A greige goods coating 212 of thermoplasticpolyolefin polymer having recurring polar moieties has been integrallyfused to the carpet precursor 200. As shown in the figure, the backloops 208 and portions of the primary backing 202 have been heat bonded(i.e., adhered or integrally fused) with the greige goods coating 212.Spaces between the primary backing 202 and the greige goods coating 212may be larger or smaller depending on the penetration of the greigegoods coating into the primary backing during manufacture. In fact, thegreige goods coating may more or less conform to the shape of the bottomsurface of the primary backing and encapsulate the back loops. Thus,there may be little, if any, space between the greige goods coating andthe primary backing. The underside 214 of the carpet product may beessentially flat due to the cooling contact made with the surface of acasting roller during processing.

[0086] During manufacture, the back loops 208 may be heated sufficientlyfor individual fibrils of the yarn to integrally fuse with each other.The preliminary heating of the carpet precursor raises the temperatureof the carpet precursor above the melting point of the yarn, melting atleast a portion of substantially all of the individual fibers of theyarn in the back loops such that the yarn fibers melt and flow together,integrally fusing the individual fibers to each other both within a tuftand between tufts of yarn. The heat of the greige goods coatingcontacting the primary backing and integrally fused fibrils of yarn alsomay partially melt the polymers therein sufficient to form a heat bondwith the greige goods coating. This enhances the mechanical durabilityof the resulting carpet product. Further, the integral fusing of thefibers lessens the need for the greige goods coating to fully wet andpenetrate the back loops of yarn. The integral fusing of the fibersaround the primary backing sufficiently secures the fibers in place suchthat the carpet material will pass the Velcro® test without completewetting by the greige goods coating of the fiber bundles.

[0087] Preferably, the primary backing comprises a thermoplasticpolyolefin polymer having recurring polar moieties in the filldirection, such that heating the carpet precursor allows the fill yarnto bond with the inside of the fiber bundle loop. A fill yarn made fromthermoplastic polyolefin polymer having recurring polar moieties,preferably a graft polyolefin polymer such as maleic anhydride modifiedpolypropylene, adheres to the innermost part of the fiber bundle backloop when heated. This provides a more secure bond between the fiberbundle back loop and the fill yarn around which it is wrapped, helpingto prevent pull-out of the fibers from the primary backing. By bondingthe internal part of the fiber bundle back loop to the fill yarn of theprimary backing, total penetration and wetting of the back loops by thegreige goods coating is no longer required to hold the fibers in place.

[0088] Alternatively, the primary backing may be coated with a primarybacking coating of thermoplastic polyolefin polymer having recurringpolar moieties before tufting the yarn through the backing. The primarybacking coating is preferably a polypropylene graft polymer with maleicanhydride. The primary backing coating is preferably in an amount offrom about 0.5 to 5.0 mils thick. Upon heating, the coated primarybacking will adhere or integrally fuse to the inside of the fiber bundleback loop, preventing pull-out of the fibers and reducing the need tototally penetrate the fiber bundles with the greige goods coating toensure sufficient tuft bond strength. Further, the primary backingcoating may adhere or integrally fuse with the greige goods coating,thereby locking the fiber back loop between the two coatings, holding itsecurely in place (see FIG. 8).

[0089]FIG. 3a depicts a carpet precursor 300 from which a level looppile carpet is made. A woven primary backing 302 is interpenetrated by amulti-fiber face yarn or bulk continuous filament (BCF) yarn 304. Suchyarn may be a twisted array of, for example, 120 small denier fibers.Yarn loops or tufts 306 form the pile of the carpet. The yarn ismechanically secured to the backing 302 by back loops 308 exposed on theunderside of the carpet precursor. In this example the BCF yarn is madeof polypropylene and the backing 302 is a woven fabric also made ofpolypropylene.

[0090]FIG. 3b depicts a carpet product 310 made from the carpetprecursor of FIG. 3a. A greige goods coating 312 of thermoplasticpolyolefin polymer having recurring polar moieties has been integrallyfused to the carpet precursor 300. As shown in the figure, the backloops 308 and portions of the backing have been heat bonded with thegreige goods coating 312. As in the example of FIG. 2a, some voids orspaces may occur between the greige goods coating and carpet precursor.Alternatively, the upper portion of the greige goods coating maypartially or totally encapsulate the back loops.

[0091] During manufacture, the back loops 308 are preferably partiallymelted so that individual fibers making up the yarn are integrally fusedwith each other by preheating of the carpet precursor before contactingit with the hot greige goods coating. The heat of the greige goodscoating may further partially melt the integrally fused fibers such thatthey heat bond with the greige goods coating and/or the primary backing302. It has been observed experimentally that this improves themechanical stability of the resulting carpet product and secures thetufts and component yarn fibers to a sufficient degree that the carpetproduct can pass the Velcro® test, as explained previously herein.

[0092]FIG. 3c depicts a carpet product 320 which includes an optionalsecondary backing 322. In this example, the secondary backing islaminated with the hot greige goods coating 312 and integrally fuseswith it. Preferably, the secondary backing is a tape yarn in both theweave and fill directions. More preferably, the tape yarn is athermoplastic polyolefin polymer having recurring polar moieties foroptimal adherence to or integral fusing with the greige goods coating.

[0093] An apparatus for producing a carpet product is illustrated inFIGS. 4a and 4 b. Carpet precursor or greige goods 430 is supplied atlocation 431 with the carpet pile facing downwardly. The carpetprecursor is placed in contact with a heated roller 432, whereby theunderside of the carpet precursor is heated. This results in heating ofthe back loops or knots of the carpet precursor which may be partiallymelted therefrom, causing the fibers of the back loops to integrallyfuse. The heated carpet precursor 434 travels downstream in theapparatus for lamination with a greige goods coating 436.

[0094] The greige goods coating may be a thermoplastic polyolefinpolymer having recurring polar moieties, such as a copolymer or a graftpolymer. The coating may be applied as a hot extrusion such as from adie as shown in FIG. 4, or as a preformed film or sheet which is heatedto allow heat bonding to the carpet precursor, which preferentially isitself preheated. The greige goods coating may be heated beforeapplication to the carpet precursor, or after contact therewith.

[0095] The heated roller 432 may advantageously be a fluid or oil heatedroller, although other means may be employed to uniformly heat thesurface of the roller, such as electrical resistance elements. Whenheated fluid is employed, the fluid enters the system at 438 (whileshown in FIG. 4a off-center, the fluid inlet is typically at the centerof the roll), is circulated in the roller 432 and exits at 440 (whileshown in FIG. 4a off-center, the fluid outlet is typically at the centerof the roll). The oil is reheated and recirculated in a closed loopsystem designated generally by numeral 441. Advantageously, the systemis operated to maintain the surface of the roller 432 at a uniformtemperature across the width of the roller. The optimum surfacetemperature of the roller is dependent on a number of variables,including the structure and composition of the carpet precursor, linespeed, roller pressure and the area of the contact between the roller432 and the carpet precursor. In the system illustrated in FIG. 4, theroller 432 is 5.9 inches in diameter. The surface of the roller may bemaintained between 330° F. and 650° F. or even higher, and preferablybetween 400° F. and 500° F. At a line speed of about 10 feet per minute,the preferred roller surface temperature was about 400 to 450° F. usingcertain common carpet precursors as described in greater detail in theexamples below.

[0096] The roller 432 may be provided with a surface or coating whichresists sticking. In the system illustrated in FIG. 4, the roller 432 iswrapped with teflon tape. A doctor blade 442 may be provided to removebuilt-up polymer melted from the underside of the carpet precursor.

[0097] Water cooled nip roll 444 may be provided which, together withthe tension in the running carpet precursor, holds the underside of thecarpet precursor against the heated roller. With reference to FIG. 4b,which shows some additional aspects of the apparatus of FIG. 4a inperspective view, the heated roller and auxiliary rollers are designated432′ and 444′, respectively. The auxiliary rollers 444′ are rotatablymounted to a pivoting bar assembly 446. The pressure of the carpetprecursor against the heated roller is controlled by applying pressureto the pivoting bar assembly 446 by means of hydraulic actuators 448.The pressure at nips 450 and 450′ have been desirably controlled toprovide a contact pressure at a tangential point between the nip rolls450 and 450′ and chill roll 432 of between 1 and 4 pounds per linearinch of width with a gap setting between the respective rolls prior tointroducing the carpet precursor of between zero and one inch. Thecontact pressure and gap setting will depend upon the thickness anddensity of the carpet precursor. In the apparatus of FIG. 4, thehydraulic pressure may typically be set at 460 to 480 pounds per squareinch to obtain the desired contact pressure at the recited gap setting.

[0098] Referring once more to FIG. 4a, the rollers 444 may be mounted sothat their axes of rotation can be selectively positioned along lines445. An additional roller 447 may be provided, whose axis of rotationmay be selectively positioned along line 449. During line start-up,rollers 44 and 47 may be moved downwardly so that the path of the greigegoods 430 is located out of contact with the heated roller 432, therebypreventing overheating of the greige goods as it is being threaded intothe line. In addition, during operation, the location of rollers 444along lines 445 may be adjusted to vary the heat input into the greigegoods. Thus, the heated roller temperature can be maintained constantand the wrap angle (i.e. residence time) of the greige goods adjustedfor line parameter variations such as greige goods weight.

[0099] As shown in FIG. 4a, the heated carpet precursor 434 travels ashort distance “d” to be laminated with the greige goods coating 436.Preferably, this distance is as short as possible to minimize heat lossfrom the carpet precursor. The heated carpet precursor 434 preferablymay contact the heated greige goods coating as it is directly extrudeddownwardly onto the underside of the carpet precursor. The greige goodscoating is formed by forcing a thermoplastic polyolefin polymer havingrecurring polar moieties feedstock 451 through an extrusion die 452. Inexamples discussed below, the extrusion die temperature is about 510° F.Alternatively, the greige goods coating may be a preformed sheet or filmmade by any method known in the art, including extrusion and casting. Itis desirable that the greige goods coating be above its meltingtemperature when it contacts the carpet precursor, advantageously 100°F. or more above its melting temperature, to assure good heat bonding.

[0100] The greige goods coating and carpet precursor together passbetween nip roll 454 and casting or chill roll 456. As shown in FIG. 4b,the nip roller 454′ may be rotatably mounted on parallel pivoting arms458. The nip roller and pivoting arms exert a pressure against the upperside of the carpet precursor which consequently presses the greige goodscoating against the casting roller 456′. A contact pressure at atangential point between the nip roller 454 and the chill roller 456 ofbetween 1 and 4 pounds per linear inch of width with a gap settingbetween the respective rolls prior to introducing the carpet precursorof between zero and one inch has been desirably utilized. The contactpressure and gap setting will depend upon the thickness and density ofthe carpet precursor. Advantageously, the casting roller is maintainedat a controlled temperature. In the examples discussed below, thattemperature is 130° F.

[0101] A carpet product 460 is produced which may be subjected toadditional processing. Optionally a secondary woven backing or non-wovenbacking (not shown) may be simultaneously laminated to the greige goodscoating 436 at the casting roll 456.

[0102] In order to control shrinking of the carpet precursor or carpetproduct, a tenter frame (not shown) may be employed during thepreheating and lamination operations or thereafter.

[0103] Various polymers have been extruded or laminated onto carpetprecursors as greige goods coatings. In particular, trials have beenconducted using polypropylene homopolymer (prime virgin 5 mils),polypropylene copolymer (recycled from shrink film), polypropylenehomopolymer (recycled from fiber), and thermoplastic elastomerpolypropylene blend ({fraction (50/50)} blend). Alternatively, otherthermoplastic polyolefin polymers having recurring polar moieties,including copolymers of ethylene, propylene and butylene with polarmonomers such as methacrylate, vinyl acetate, acrylic acid, methacrylicacid, ethyl acrylate, butyl acrylate and vinyl alcohol, or graftpolymers of polyethylene, polypropylene and polybutylene with polarmoieties such as maleic anhydride, may be used as greige goods coatings.In all the trials, the extruded sheet exhibited good bonding strength tothe back of the carpet. The greige goods used in the trials included apolypropylene primary backing with polypropylene face fiber and apolypropylene primary backing with nylon face fiber. In addition,certain carpet trials included a secondary backing of wovenpolypropylene. The secondary backing was found to exhibit good adhesionwith all the polymer types listed.

[0104] The extrusion trials were conducted with a 1.5 inch diameter,24:1 (barrel length to diameter ratio) Sterling extruder. The extruderhad a 20 horsepower DC drive and a single stage screw. The extruder wasequipped with three heating zones, a screen pack collar and a pressuregauge. Speed was controlled by a variable resistor dial and a tachometerwas connected to an RPM dial for speed indication. Typical extrudertemperatures range from 340° F. to 600° F. and pressures from 1000-3000psi. Typical die melt temperatures range from 450-580° F.

[0105] The apparatus used in the examples described below included aheated roller of the type shown in FIG. 4. In that apparatus, the diewidth was 12 inches. The molten polymer from the die was deposited on awater cooled casting roll (7.9 inch diameter, 13 inch width). Water waspassed through helical passages within the casting roll at high velocityto cool the casting roll as required. The nip roll was 3 inches indiameter. The casting roll assembly was driven by an eddy current clutchand a 1.5 horsepower motor.

[0106] While speeds of 10 feet per minute were actually used in theexamples described below, it is contemplated that higher speeds would beused in commercial production. In particular, since there is no dryingstep, speeds of 100 to 300 feet per minute appear possible. Carpetwidths of 12 to 15 feet may be produced. Such speeds and widths requireappropriate material and handling capability to move large rolls in andout of the process quickly. Thus, in contrast to conventional processes,the factor limiting line speed may be material handling and not theconventional adhesive drying step, which is eliminated in the practiceof the present method.

[0107]FIG. 5a presents a calculated temperature profile for theapparatus of FIG. 4 in graphical form. Temperature is represented on thevertical axis; time/position is represented on the horizontal axis.Trace 500 represents the back loop temperature at various points in theprocess designated by letters A though E which correspond to similarlylabeled locations in the apparatus of FIG. 4(a). Trace 504 representsthe carpet face temperature at the points A though E of FIG. 4(a). Thedotted line 504 represents the melting temperature of the back loopyarn. FIG. 5a illustrates a temperature profile in which the back loopsare maintained above their melting temperature, while the temperature ofthe carpet face always remains below the melting temperature.

[0108] The temperature of the carpet product at various depths (w) as afunction of time (processing stage) was simulated. FIG. 5b is an exampleof such a simulation, and contains plots of temperature at three depths,w1, w2 and w3, which are respectively 2 mils, 6 mils and 14 mils intothe backside of the carpet base. The simulation is based on thefollowing assumed properties and parameters:

[0109] Material=polypropylene; mp 325° F.

[0110] Line Speed=20 ft per minute

[0111] Ambient temperature=90° F.

[0112] Temp. of melt at extrusion die=480° F.

[0113] Temp. of casting roller=100° F.

[0114] Temp. of heated roller surface=420° F.

[0115] Cast roller diameter=5.9 ft.

[0116] Cast roller wrap angle=200°

[0117] Heated roller diameter=5.9 ft.

[0118] Heated roller wrap angle=220°

[0119] The times indicated as A, B and C correspond to the similarlylabeled locations in the apparatus of FIG. 4a. More specifically, time Acorresponds to t=o, time B corresponds to t=t (the time at which thecarpet base leaves the heated roller), and time C corresponds to t=t₂(the time when the extruded sheet first comes into contact with thecarpet base). The time t₃ is the time when the carpet product leaves thecast roller.

[0120] The following table presents a summary of simulations, includingthe simulation described in connection with FIG. 5(b), which is labeledExample 5 in the table. Heated Wide Prefusion Temp. Teflon Angle (° F.)Between Temp. After (t2) Temp. at (t3) Coating Coated on Time Time Timet>, t, and t > t₂ (Maximum) (° F.) (° F.) Thickness Roll Temp Prefuse t₁t₂ t₃ Point Point Point Ex. (mils) (° F.) Roll (sec.) (sec.) (sec.) w1w2 w3 w1 w2 w3 w1 w2 w3 1 10 120 90 1.158 2.658 5.233 120 <120  <120 390 300 220 250 240 505 2 10 420 90 1.158 2.658 5.233 400 350 260 450400 305 270 260 <260  3 — 420 90 1.158 2.658 5.233 400 350 260 NoExtruded 155 149 129 Sheet 4  5 420 90 1.158 2.658 5.233 400 350 260 430370 275 195 205 205 5  5 420 220  2.832 4.332 6.906 405 380 320 430 380320 195 215 230

[0121] Examples 1 and 2 compare a simulated process with and withoutheat being applied to the heated roller. Example 3 illustrates theeffect on the simulation of eliminating the greige goods coating.Examples 4 and 5 employ a 5 mil extruded coating and compare the processfor a heated roll wrap angle of 90° (Example 4) and 220° (Example 5).Examples 1-4 have a cast roller wrap angle of 90°. As indicated above,Example 5 has a cast roller wrap angle of 200°.

[0122] The examples illustrate how process parameters may be used tocontrol the internal temperatures of the carpet product at variousdepths to achieve melting of yarn fibers and integral fusing of yarnfibers with each other and with the greige goods coating and primarybacking, without thermally degrading the face yarn or primary backingduring processing.

[0123] The carpet base of preferred embodiments of the present inventionis a woven polypropylene primary carpet backing. This backing is wovenfrom polypropylene tapes (tape thickness 1.0 to 2.0 mils). Preferably,one tape is a modified tape of thermoplastic polyolefin polymer havingrecurring polar moieties, preferably in the fill direction. Thethermoplastic polyolefin polymer having recurring polar moieties mayconsist of an ethylene, propylene or butylene copolymer, or graftpolymer of polyethylene, polypropylene or polybutylene. Preferably, themodified tape is a graft polymer of polypropylene and maleic anhydride.The tapes are machine direction oriented to arrive at tensile strengthsin the range of about 4 to 6 grams per denier. Orientation of thethermoplastic polyolefin polymer involves organization of thecrystalline structure by controlled handling and cooling duringproduction. This process makes it possible to make the backing strongenough for the end carpet use. However, the backing cannot be heated fortoo long to a temperature above the original orientation temperature(240 to 280° F.) without damaging the orientations of the thermoplasticpolyolefin polymer. If the orientation is lost substantially throughoutthe tape thickness, the strength of the backing is compromised.

[0124] It will be clear from the foregoing that variable wrap angles maybe used at a constant line speed to change the internal carpettemperatures without changing the apparatus temperature settings or theprocess speed. The process response to a wrap angle change is relativelyinstantaneous. The process response to apparatus temperature setting andline speed changes is much slower (i.e., it takes a relatively long timeto reach the desired equilibrium process temperature at points w1, w2,and w3).

[0125] This feature is very important, particularly for a commercialcarpet manufacturer who must routinely make many varieties of carpet(e.g. often the same carpet style will be offered in one color line butat three different face fiber weights or qualities). In such cases,adjustment of the wrap angles can provide the necessary heat adjustment(to accommodate the three different face weights) on the fly. Likewise,adjustment of wrap angles may facilitate start-up of a line and avoidburning through the carpet base when the line runs initially at a slowspeed.

[0126] While adjustment of line speed and process temperature settingsmay be used, the temperatures w1, w2 and w3 reach equilibrium much moreslowly and involve more complicated interactions.

[0127]FIG. 6 is a schematic side view of an alternative embodiment ofthe present invention. The underside of a carpet precursor 600 is passedin contact with an electrically heated plate 602. The carpet precursor600 may be pressed between the electrically heated plate 602 and asecond plate 604 whose temperature is not controlled. Preferentially,electrically heated plate 602 is oriented at an angle with respect tosecond plate 604 in order to gradually increase the pressure exerted onthe carpet precursor and iron the back loops as the carpet precursormoves from right to left across the electrically heated plate 602.Successful trials of the apparatus have been run where the surfacetemperature of the plate 604 was set at 600° F. Alternatively, a radiantheater (not shown) may be substituted for the heated plate 602.

[0128] With continuing reference to FIG. 6, heated carpet precursor 606is drawn to the nip 607 formed between nip roller 608 and casting roller610. A greige goods coating 612 is extruded directly onto the undersideof the heated carpet precursor from extrusion die 614. Casting rolltemperatures between 80 and 120° F. have been employed. Pressures ofbetween 50 to 70 psi at the nip 607 have been employed.

[0129] Temperature variations across the heated plate 602 have beenobserved to produce variation across the width of the carpet product.Cool areas produce regions in loop pile BCF carpet, for example, whichfail the Velcro® test. Hot areas produce regions of apparent excessshrinkage and face yarn damage. In addition, the hot areas may depositexcessive melted polymer from the greige goods coating onto the heatedplate.

[0130]FIG. 7 is a schematic side view of another embodiment of thepresent invention. In FIG. 7, a carpet precursor 700 is supplied to theapparatus, pile side down. A sheet 702 of greige goods coating is alsosupplied to the apparatus. The sheet 702 may either be freshly extrudedin a manner similar to that described above, or it may be formed at adifferent time and/or location and supplied from a feed roll.

[0131] The apparatus of FIG. 7 includes a first differentially heatedand cooled surface 704. The surface functions both as a heated surfacefor integrally fusing the greige goods coating sheet 702 to the carpetprecursor 700 and as a casting surface for forming and cooling theunderside of the carpet product.

[0132] In preferred embodiments of the present invention, the surface704 is a continuous belt which travels around heated cylinder 706 andcooled cylinder 708. Stationery heating and cooling units 710 and 712,respectively, may also be provided to adjust the temperature profilearound the path of travel of the belt 714.

[0133] In operation, the belt is differentially heated so that it isrelatively hot at location 714 where it first contacts the greige goodscoating sheet 702. At a downstream location 716, the heated greige goodscoating sheet contacts the carpet precursor, the combination of which ismoved and cooled as the belt travels from left to right in FIG. 7.

[0134] A lower continuous belt system 718 may be provided for applyingpressure to the upper side of the carpet product. An upper surface 720of the lower belt may be oriented at an angle with respect to the upperbelt as illustrated in order to gradually increase the pressure exertedon the carpet product. The temperature of the lower belt 718 may also becontrolled in a manner similar to belt 704, albeit at lowertemperatures.

[0135] At location 722, the carpet product and belt are sufficientlycool that the carpet product readily separates from the belt withoutleaving significant amounts of melted polymer (preferably no meltedpolymer) on the belt 704. From this location the carpet product travelsdownstream in the production line.

[0136]FIG. 8 is a cross-sectional view illustrating a carpet andcarpet-making process in accordance with a more preferred embodiment ofthe present invention. In the Figure, processing distances have beencompressed for illustration purposes, and processing steps illustratedschematically. Though this process is shown as a continuous process, itwill be understood that various steps may be performed on differentmanufacturing lines at different times. The illustrated process beginswith a primary backing 800 (shown here as a woven primary carpet backingwith warp strands 802 and fill strands 804). Advantageously the primarybacking is made of thermoplastic polyolefin polymer having recurringpolar moieties.

[0137] A thermoplastic primary backing coating 806 may be applied to theprimary backing 800. This layer may be omitted in some embodiments.Preferably, the primary backing coating 806 is produced by extruding athermoplastic polyolefin polymer having recurrent polar moieties ontoone side of the primary backing 800 from extruder 808. Yarn 810interpenetrates the coated primary backing 812. Advantageously, the yarnmay be a nylon multi-filament yarn. The yarn is tufted, looped orpunched through the coated primary backing to form back loops such as814.

[0138] At the indicated location, pressure and/or heat may be applied tothe product. This process may be performed by the heated roller systemsdescribed above. Where the yarn is multi-filament yarn, at least aportion of the back loop will be heated above the melting point of theyarn material so that at least a portion of substantially all of thefilaments integrally fuse to one another. If the yarn is nylon, this mayrequire temperatures in the range of 520° F. to 550° F. Because the yarnis typically twisted, it will be understood that this step may requireheating only a portion (for example about 50%) of the thickness of theyarn to a temperature and pressure sufficient to affect integral fusing.

[0139] At a point later in the process, a second thermoplastic layer, orgreige goods coating, 816 is applied to the carpet product. In apreferred embodiment, this layer is produced by extruding a secondthermoplastic polyolefin polymer having recurrent polar moieties ontothe carpet base 812 from extruder 818. The greige goods coating may beextruded in hot, essentially molten, form directly onto the carpetproduct while the carpet base is still hot from the heating and pressingstep.

[0140] The end product of various of the processing steps depicted inFIG. 8 may have some or all of the following advantageous features:

[0141] (1) Integrally fused filaments (such as nylon filaments) in theback loops of the yarn, whereby the finished carpet resists fuzzing.

[0142] (2) A primary backing 800 of thermoplastic polyolefin polymer(especially one having recurring polar moieties) integrally fused oradhered with the primary backing coating 806 such as at interface 820.

[0143] (3) A primary backing 800 of thermoplastic polyolefin polymer(especially one having recurring polar moieties) integrally fused oradhered with the integrally fused filaments in the back loops 814.

[0144] (4) A primary backing coating of thermoplastic polyolefin polymerhaving recurring polar moieties adhered or integrally fused to innerportions of carpet back loops, such as at interface 822.

[0145] (5) Pressure flattened back loops such as at 824 onto whichfurther layers or backings may readily be applied. The back loopsthemselves may be integrally fused to one another.

[0146] (6) A greige goods coating 816 adhered or integrally fused to thelower portions of the back loops and/or the primary backing coating 806such as at interface 826.

[0147] (7) A greige goods coating 816 integrally fused or adhered toportions of the primary backing 800 and/or primary backing coating 806such as at interface 828.

[0148] (8) An extruded and cast greige goods coating 816 to whichfurther layers or backings may be readily adhered or integrally fused.

[0149] One product of the foregoing process is a durable carpet withnylon face yarn and a flexible, rollable polyolefin based backing whichhas physical properties described in the art as a “good hand.”

EXAMPLES

[0150] The process parameters for preparing the carpet products of thefollowing inventive Example 1 and Comparative Example appear in thefollowing table. Example 1 Comparative Example 2 Extrusion Temp. (° F.)600 575 Back Pressure (psi) 430 710 Greige Goods Coating  10  10Thickness (mils) Nip Pressure (psi)  90  80 Drum Temp. (° F.) (hot oil)475 Not Applicable Face Fiber nylon nylon Greige Goods modified poly-ethylene methacrylate Coating Material propylene (EMA) Velcro TestResult very good; little fair to poor; moderate to no fuzz to heavy fuzz

Example 1

[0151] A sample of carpet of the present disclosure was preparedaccording to the methods described herein. In particular, a nylon facefiber was tufted on a primary backing, to form a carpet precursor. Theback side of the formed carpet precursor was heated on a hot oil drum ata temperature of 475° F. to pre-fuse the nylon face fibers tothemselves. A greige goods coating of a polypropylene graft polymer withmaleic anhydride manufactured by Morton Chemical under the name of Tymor212599-2 was extruded in molten form from a die at a temperature of 600°F. onto the pre-fused carpet precursor at a thickness of 10 mils. Thecoated carpet precursor was then run through a nip roll at a nippressure of 90 psi and a back pressure of 430 psi before cooling. AVelcro test performed 24 hours after formation of the carpet productindicated a very good bond with little to no fuzzing, indicative ofintegral fusing of the nylon fibers to themselves and good adhesion orintegral fusing between each of the greige goods coating, primarybacking and fused fibers.

Comparative Example

[0152] This example was prepared using a nylon face fiber and a greigegoods coating of ethylene methacrylate (EMA) (24% methacrylate content)provided by Exxon. This sample was not pre-fused or pre-heated. Aftertufting, the carpet precursor was contacted with the greige goodscoating extruded at a temperature of 575° F. to a thickness of 10 mils.The nip pressure was 80 psi, and the back pressure was 710 psi. TheVelcro test, performed 24 hours after formation of the carpet product,resulted in moderate to heavy fuzz, with large numbers of individualfibers being pulled out of the carpet product.

Example 2

[0153] A carpet is made having a nylon face fiber and a primary backingof polypropylene in the warp direction and maleic anhydride graftpolypropylene polymer in the fill direction. Upon preheating to atemperature of about 460-550° F., portions of substantially all of thenylon fibers integrally fuse together, and the fill yarn adheres to theinside portion of the nylon fiber back loop. The pre-fused carpetprecursor is coated with about 10 mils of extruded maleic anhydridegraft polypropylene polymer and cooled. The greige goods coatingintegrally fuses to at least the fill yarn of the primary backing andadheres to the nylon fibers. The carpet thus made will have little to nofuzz and a high tuft pull strength.

Example 3

[0154] A carpet is made having a nylon face fiber and a primary backingof polypropylene coated on one side with a primary backing coating ofethylene methacrylate. Upon preheating to a temperature of about460-550° F., portions of substantially all of the nylon fibersintegrally fuse together, and the primary backing coating adheres to theinside portion of the nylon fiber back loop. The preheated carpetprecursor is coated with about 10 mils of extruded ethylene methacrylateand cooled. The greige goods coating integrally fuses to at least theprimary backing coating and adheres to the nylon fibers. The carpet thusmade will have little to no fuzz and a high tuft pull strength.

[0155] As shown by the above Examples, the most preferred embodiments ofthe invention described herein are as follows:

[0156] (1) A carpet having a primary backing, preferably ofpolypropylene, a face yarn made up of a plurality of nylon fibers tuftedin the primary backing so that back loops of yarn are on the undersideof the primary backing, wherein the nylon fibers are integrally fusedtogether by pre-heating, and a greige goods coating of a thermoplasticpolyolefin polymer having recurring polar moieties, preferably a maleicanhydride graft polymer of polypropylene, applied to the carpetprecursor after pre-heating so that the greige goods coating adheres toone or more of the integrally fused fibers and primary backing.

[0157] (2) A carpet having a primary backing wherein the fill yarn is athermoplastic polyolefin polymer having recurring polar moieties,preferably a maleic anhydride graft polymer of polypropylene, a faceyarn made up of a plurality of nylon fibers tufted in the primarybacking so that back loops of yarn are on the underside of the primarybacking, and a greige goods coating of thermoplastic polyolefin, whereinthe fill yarn adheres to the inside of the nylon fiber back loop.

[0158] (3) A carpet having a primary backing coated with a thermoplasticpolyolefin polymer having recurring polar moieties, preferably ethylenemethacrylate, a face yarn made up of a plurality of nylon fibers tuftedin the primary backing so that back loops of yarn are on the undersideof the primary backing, and a greige goods coating of thermoplasticpolyolefin, preferably of the same composition as the primary backingcoating, wherein the inside of the back loops of the face yarn adheresto the primary backing coating, and the primary backing coating andgreige goods coating integrally fuse, locking the yarn fibers in place.

[0159] From the foregoing description, one of ordinary skill in the artcan ascertain the essential characteristics of the present invention,and without departing from the spirit and scope thereof, can makechanges and modifications of the disclosed techniques to adapt them tovarious uses and conditions. As such, these changes and modificationsare properly within the scope of the range of equivalents of thefollowing claims.

We claim:
 1. A method of making a carpet comprising: tufting a primarybacking with yarn to form a carpet base with portions of the yarnprotruding from the upper side of the primary backing and with back loopportions of the yarn exposed on the underside of the primary backing;heating the underside of the carpet base to heat the back loop portionsof the yarn sufficient to integrally fuse the individual fibers of theyarn together; applying a greige goods coating of a thermoplasticpolyolefin polymer having recurring polar moieties onto the underside ofthe carpet base, whereby said greige goods coating adheres to fibers inthe back loops.
 2. The method of claim 1, wherein the yarn, greige goodscoating and primary backing are integrally fused.
 3. The method of claim1, wherein the greige goods coating is 3 to 15 mils thick.
 4. The methodof claim 1, wherein the primary backing comprises polypropylene.
 5. Themethod of claim 4, wherein the primary backing comprises propylenecopolymer or polypropylene graft polymer in one or more of a warp or afill direction and is adhered to the integrally fused fibers.
 6. Themethod of claim 4, wherein the primary backing comprises propylenecopolymer or polypropylene graft polymer in one or more of a warp or afill direction and is integrally fused to the integrally fused fibers.7. The method of claim 1, further comprising contacting a second backingto the greige goods coating such that the greige goods coating isbetween the primary backing and second backing.
 8. The method of claim7, wherein the second backing comprises polyolefin tape yarn in both thewarp and fill directions.
 9. The method of claim 1, wherein the yarnfibers are selected from the group consisting of nylon, polypropylene,polyester, polyethylene, acrylic and a combination thereof.
 10. A methodfor manufacturing a carpet comprising; coating a primary backing with aprimary backing coating of a thermoplastic polyolefin polymer havingrecurring polar moieties; fixing tufts of carpet fibers to the coatedprimary backing so that the tufts protrude from the top surface of thecoated primary backing to form a tufted base and back loop portions ofthe carpet fibers are exposed on the underside of the primary backing;applying a greige goods coating of a thermoplastic polyolefin polymer toat least one of the coated primary backing or back loops.
 11. The methodof claim 10, further comprising the step of applying a second backingsuch that the greige goods coating is between the primary backing andsecond backing.
 12. The method of claim 11, wherein the second backingcomprises polyolefin tape yarn in both the warp and fill directions. 13.The method of claim 10, wherein the step of applying the greige goodscoating integrally fuses the greige goods coating to one or more of thefiber back loops and the coated primary backing.
 14. The method of claim10, wherein the primary backing coating comprises a graft polymer ofpolypropylene and maleic anhydride.
 15. The method of claim 10, whereinthe yarn fibers are selected from the group consisting of nylon,polypropylene, polyester, polyethylene, acrylic and a combinationthereof.
 16. The carpet of claim 10, wherein the greige goods coating isa thermoplastic polyolefin polymer having recurring polar moieties. 17.The method of claim 10, further comprising integrally fusing the fibersto themselves.
 18. The method of claim 17, wherein the fibers areintegrally fused at a temperature at least 50° F. greater than themelting point of the fibers.
 19. The method of claim 18, wherein thefibers are integrally fused at a temperature at least 100° F. greaterthan the melting point of the fibers.
 20. A method of making a carpetcomprising: forming a primary baking comprising a polypropylene tape inone direction and a tape of thermoplastic polyolefin polymer havingrecurring polar moieties in the other direction; tufting the primarybacking with yarn to form a carpet base with portions of the yarnprotruding from the upper side of the primary backing and with back loopportions of the yarn exposed on the underside of the primary backing;and applying a greige goods coating of a thermoplastic polyolefinpolymer to the underside of the carpet base, whereby said greige goodscoating adheres to the fibers of the back loops.